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Wondering if anyone has used a refractometer or knows of any other method to measure a coffee extraction (or dissolved solids)?

  • Interesting. You could also measure the difference in mass of the grounds before and after extraction, but you need to get the dry weight of the grounds after. You could gently dry in a kiln or oven, but you'd also need to normalize for any pre-infusion water in the beans... – hoc_age Sep 30 '15 at 13:22
  • If I understand your question correctly, a refractometer is not what you would use. A refractometer measures pure substances or combinations of them in solution. Coffee contains both dissolved pure ingredients and suspended ingredients. @hoc_age's approach may be the best. A nephelometer measures turbidity, and this might also work. – daniel Nov 12 '15 at 13:34
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I guess measure density just like you would in a college-lab? Just use a graduated cylinder.

Extraction is mostly about how efficiently you can extract coffee solubles with an amount of liquid. Since refractometers are pricy, you can use a 0.1g scale and a graduated cylinder, to measure how heavy your shots are. The denser the better, however you also have to be practical with how long your shots take to be pulled.

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    Could you pleaae explain how this method will help? – MTSan May 14 '16 at 23:38
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    Extraction is mostly about how efficiently you can extract coffee solubles with an amount of liquid. Since refractometers are pricy, you can use a 0.1g scale and a graduated cylinder, to measure how heavy your shots are. The denser the better, however you also have to be practical with how longy your shots take to be pulled. Advanced machines nowadays have a 45-second standard for espresso. Apologies for being vague. – wearashirt May 15 '16 at 8:56
  • @wearashirt - With the addition of your comment, I think you've got it. Assuming you have accurate enough measurement instruments (volume, mass, maybe temperature), you can determine density, and therefore how much coffee content you have extracted. You'd have to be fiendishly exact, to the point where the temperature matters; 25mL of pure water at near-boiling/~100C would only be 24g! Would you consider editing your comment content (and this content, if you'd like) into your answer? It would be much improved. – hoc_age May 17 '16 at 0:04
  • @hocage, wearahirt, I cannot get the idea. For example, Hario scale has a 0.1 g accuracy, and seconds for timing. Brewing cups has very nice levels for volume. Still, you cannot notice any difference in the density. I think this is not possible in practice. – MTSan May 17 '16 at 9:39

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